JPH10121114A - Production of porous sintered metallic tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a means of efficiently sintering a porous sintered metallic tube having different characteristics on the inside and outside surfaces in the method for producing a porous sintered metallic tube in which a preliminarily formed body is heated and sintered. SOLUTION: A solid-liq. mixed body contg. grains for forming a primary layer is charged into a cylindrical die 3 rotating at a high speed and is centrifugally formed to form a primary layer 1, metallic grains for forming a secondary layer are fed to the inside of the primary layer 1 to form a tubular double- layered preliminarily formed body integrally formed with the primary layer 1, and the double-layered preliminarily formed body is sintered. As for a suitable sintering method, the double-layered preliminarily formed body is sintered under isotropic pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a porous sintered metal tube, and more particularly, to a method for manufacturing a porous sintered metal tube in which a preform is heated and sintered.

[0002]

2. Description of the Related Art Conventionally, in a method for manufacturing a porous sintered metal tube, as shown in FIG. 6, a carbon filled space in which a cylindrical filling space is previously formed is used for manufacturing a porous sintered metal tube. From the filling port 6a of the steel capsule 6, granular stainless steel (JIS S) which is a metal filter material is inserted into the capsule 6.
US316L) (see FIG. 1A), and the inside of the capsule 6 is degassed via the filling port 6a.
a is sealed (see FIG. 2B). The sealing is performed by electron beam welding in a vacuum chamber. The granular stainless steel sealed in the capsule 6 is charged into an isotropic pressure press and heating device (hereinafter, referred to as a HIP device), and is heated and sintered under isostatic pressure. The sintered stainless steel porous body after sintering is removed from the HIP device, and the capsule 6 is removed to form a cylindrical metal filter (see FIG. 3C).

[0003]

In the above-mentioned conventional method for producing a porous sintered metal tube, the molding particles are encapsulated in capsules 6.
It is extremely difficult to arrange different molding particles on the inner and outer surfaces to fill the inside, and it is impossible to produce a sintered metal tube having different characteristics on the inner and outer surfaces by a single molding and sintering. Was. In order to cope with this problem, it is conceivable to attach the second molding particles to the surface of the tubular pre-sintered body once pre-sintered and sinter it. It is difficult to form a thin layer uniformly, and it is necessary to scrape off a layer previously formed to a thickness greater than necessary. Therefore, in order to manufacture a sintered metal tube having different characteristics on the inner and outer surfaces, a preformed tubular body is arranged in a capsule, a filling space is formed on the surface, and the second molding particles are filled. Although it is conceivable to sinter it, there is a required wall thickness to prevent the shape of the tubular body from being lost, and in order to produce a thinner body, finishing of the surface of the tubular body is required. There is a problem that processing is also required and a great deal of work is required. Therefore, a method for manufacturing a porous sintered metal tube according to the present invention solves the above-mentioned problems and provides a means for efficiently sintering a porous sintered metal tube having inner and outer surfaces having different characteristics. With the goal.

[0004]

[Means for Solving the Problems]

[First characteristic configuration] A first characteristic configuration of the method for manufacturing a porous sintered metal tube of the present invention for the above-mentioned object is as follows. The solid-liquid mixture containing the particles for forming one layer is charged and centrifuged to form
Forming a layer, supplying metal particles for forming a second layer inside the first layer to form a tubular multilayer preform formed integrally with the first layer, and forming the multilayer preform. The point is to sinter the body. [Operation and Effect of First Characteristic Configuration] According to the first characteristic configuration, a porous sintered metal tube having different characteristics on the inner and outer surfaces can be manufactured only by a single preforming step. That is, since the metal particles for forming the second layer are supplied and centrifugally molded inside the preformed body of the first layer which has been centrifugally formed while the first layer is arranged in the mold, the second layer is formed. The metal particles for use can be easily integrated with the first layer to form a multilayer preform.
Therefore, a multilayer preform can be formed in a single molding step. As a result, even if the first layer is thin, it can be easily handled as a multilayer preform having a metal particle layer formed inside. As a result, it has become possible to provide a means for efficiently sintering a porous sintered metal tube having inner and outer surfaces having different characteristics.

[Second characteristic configuration and operation and effect] The second characteristic configuration of the method for manufacturing a porous sintered metal tube of the present invention is the first layer in the first characteristic configuration. The forming particles and water are pre-slurried and injected into a rotating mold to form a solid-liquid mixed layer. The solid-liquid mixed layer is solidified to form a first layer, and then a second layer is formed. The metal-water slurry prepared by adding water to the metal particles for injection is poured into the inside of the first layer, and dehydrated to integrate the layer composed of the metal particles for forming the second layer with the first layer. Thus, the multilayer preform is solidified and formed, whereby a porous sintered metal tube having a first layer having a uniform thickness can be easily formed. That is,
Since the solid-liquid mixed layer is formed by slurrying the particles for forming the first layer, the thickness of the solid-liquid mixed layer is made uniform by the centrifugal force field. In addition, since it can be formed in a thin layer, even if it is a porous sintered metal tube having a thin outer surface layer, it can be integrated with the layer of metal particles for forming the second layer without giving the first layer shape retention. Can be formed. If a binder is used for the slurry for the first layer and the same kind of binder is used for the metal-water slurry, a multilayer preform that is surely formed integrally through the binder can be formed. As a result, molding of the multilayer preform in the first characteristic configuration is further facilitated.

[Third Characteristic Configuration] A third characteristic configuration of the method for manufacturing a porous sintered metal tube according to the present invention is as follows. After dispersing the layer-forming particles, water to which a binder is added is added to the dispersed first-layer forming particles to form a solid-liquid mixed layer, and the solid-liquid mixed layer is solidified to form a first layer. After the formation, the metal particles for forming the second layer are supplied to the inside of the formed first layer, and the layer composed of the metal particles for forming the second layer is integrated with the first layer to form a multilayer preform. And sintering the multilayer preform. [Operation and Effect of Third Feature Configuration] The above-described first feature configuration provides the same operation and effect as the second feature configuration. That is, by dispersing only particles in advance, the first layer having a uniform inner diameter determined by the rotation speed of the mold can be formed.
If water to which a binder is added is injected from the inside, the binder infiltrates with the water into the first layer, so that a solid-liquid mixed layer is easily formed. Therefore, for example, if the excess water is added, and after the first layer is solidified, the metal particles for forming the second layer are supplied to the inside, the binder acts together with the excess water to form the metal layer integrally. A multilayer preform can be formed. As a result, similarly to the second characteristic configuration, it is possible to provide a means for facilitating the molding of the multilayer preformed body and efficiently sintering the porous sintered metal tube having the inner and outer surfaces having different characteristics. It became so.

[Fourth characteristic configuration and operation and effect] The fourth characteristic configuration of the method for manufacturing a porous sintered metal tube of the present invention is as follows.
As described in claim 4, inorganic particles are used for the first layer forming particles in any of the first to third characteristic configurations,
The point is to use metal particles having a larger particle size than the first layer forming particles for the layer forming metal particles, thereby providing, for example, a fine transmission hole in the outer surface portion, such as used in a filter, The inner layer has a larger transmission hole diameter than the outer surface portion,
It can be formed on a porous metal layer having high strength, and can be used as a support layer of a filter. By forming the outer surface portion with fine particles having a small particle diameter, the specific surface area of the outer surface portion can be increased.If the outer surface portion is formed as a catalyst layer, a highly efficient catalyst layer can be obtained. It is possible. In this case, for example, it is more effective if the first layer forming particles are composed of catalyst particles. As a result, a porous sintered metal tube effective for a filter, a catalyst layer, and the like can be easily manufactured.

[Fifth characteristic configuration and operation and effect] Further, the fifth characteristic configuration of the method for manufacturing a porous sintered metal tube of the present invention is as follows.
The first metal having a higher recrystallization temperature than the recrystallization temperature of the second layer forming metal particles as the first layer forming particles according to any one of the first to fourth characteristic configurations, as described in claim 5. The use of particles makes it easy to form, for example, a metal filter in which the minimum blocking particle size is accurately controlled. In other words, the diameter of the through-hole of the sintered metal body basically depends on the particle diameter of the constituent metal particles, but the diameter of the through-hole is reduced by oversintering. Since the recrystallization temperature is higher than the particles, oversintering of the first layer forming metal particles can be easily prevented.

[Sixth characteristic configuration and operation and effect] The sixth characteristic configuration of the method for manufacturing a porous sintered metal tube of the present invention is as follows.
According to a sixth aspect of the present invention, the multilayer preform of any one of the first to fifth features is sintered under isostatic pressure. By sintering under the isostatic pressure, for example,
Even when the particle size difference between the first layer forming particles and the second layer forming particles is large, sintering can be performed at a relatively low temperature. Shrinkage can be prevented, and reduction in the diameter of the transmission hole can be prevented. Further, there is a difference in material between the first layer forming particles and the second layer forming particles,
Even when the melting points are significantly different, sintering can be performed at a relatively low temperature by the effect of isotropic pressure pressing, so that sintering between the first layer forming particles and the second layer forming particles can be promoted. In addition, integration by sintering becomes easy. Furthermore, since sintering between materials that are difficult to join such as metal and ceramic material is also possible, for example, a ceramic material powder such as an oxide catalyst is used for the first layer forming particles and the second layer forming Even when particles of a material having relatively poor sinterability, such as stainless steel, are used as particles, sintering in which both layers are integrally formed becomes possible. As a result, a porous sintered metal tube effective for a filter, a catalyst layer, and the like can be easily manufactured.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION As an example of an embodiment of the method for producing a porous sintered metal tube according to the present invention, fine particles having an average particle diameter of 10 μm are arranged on the outer surface and the inner part is formed in a range of 150 to 1000
An example of manufacturing a filter having a minimum blocking particle size of 3 μm made of stainless steel (SUS316L) having coarse particles having a particle size distribution of μm will be described below with reference to the drawings. The dimensions of the filter to be manufactured are 114m outside diameter
m, thickness 2 mm, length 500 mm.

First, as shown in FIG. 2, the mold body 3a
A filter paper 7 is adhered to the inside of the filter, and while the drive shaft 3d is driven and rotated at a rotation speed of 500 rpm around its axis, a solid slurry composed of a water slurry of the first layer forming particles to which the binder is added is formed. The liquid mixture 4 is injected into the mold 3 (see FIG. 2). The solid-liquid mixture 4 is previously mixed and prepared, and 100 parts by weight of stainless steel (SUS316L) powder having a maximum particle diameter of 32 μm and an average particle diameter of 10 μm, 3 parts by weight of an acrylic acid polymer as a binder, and 15 parts by weight of water Are suspended in a medium dissolved in water. The viscosity of the solid-liquid mixture 4 is about 1.1 Pa · s. In addition, a plurality of dewatering holes 3e having a hole diameter of 1 mm are formed in the peripheral wall of the mold body 3a to facilitate dehydration after slurry injection described later.

When the injection of the predetermined amount of the solid-liquid mixture 4 is completed, the rotation speed of the mold 3 is increased to 1500 rpm.
The first layer 1 composed of the solid-liquid mixed layer 4A is formed by dehydration through the dewatering holes 3e via the filter paper 7. The filter paper 7 is attached in order to prevent the fine particles for forming the first layer from leaking out during the dehydration. When the dehydration is completed, the metal-water slurry 5 containing the metal particles for forming the second layer is injected from the injection hopper H inside the first layer 1 as shown in FIG. The metal-water slurry 5 is also preliminarily mixed and adjusted, and stainless steel (SUS316 having a particle size range of 150 to 1000 μm as the second layer forming metal particles) is used.
L) A powder obtained by suspending 500 parts by weight of a powder in a medium in which 60 parts by weight of an acrylic acid polymer as a binder is dissolved in 60 parts by weight of water. The viscosity of the metal-water slurry 5 is about 2.7 Pa · s.

After the metal-water slurry 5 is supplied, the rotation at 1500 rpm is maintained for about 1 hour, and the mold 3 is heated from the outside and maintained at about 100 ° C. for about 12 hours for drying. The metal particles for forming the second layer are integrated and solidified with the first layer 1 by the action of the binder to form the multilayer preform 2 (see FIG. 3). Thereafter, the injection-side end plate 3c is removed, and the multilayer preform 2 is extracted from the mold body 3a (see FIG. 4). At this time, since the metal particles are sufficiently bonded to each other by the action of the binder, the multilayer preform 2 has a sufficient shape-retaining property, and can be easily extracted without collapsing during extraction. it can.

The extracted multilayer preform 2 is encapsulated in a capsule and heated to 400 ° C. at a rate of 50 ° C./hour in an isotropic pressure sintering apparatus (a so-called HIP apparatus).
After degreasing for 5 hours, the temperature is further increased to 1230 ° C. at a rate of 100 ° C./hour, and sintering is performed under isostatic pressure of 98 MPa for 5 hours to produce a filter. The sintered filter is removed from the HIP device, and the capsule is removed to obtain a product (not shown). The resulting product is a cylindrical filter with a minimum blocking particle size of about 3 μm, made of a sintered body of stainless steel particles with a particle size range of 150 to 1000 μm, having a stainless steel particle layer with an average particle size of 10 μm on the outer surface. . The average internal pore diameter was about 50 μm.

Solid-liquid mixture 4 in which stainless steel powder is suspended in a medium using acrylic acid polymer as a binder
As shown in the cross-sectional view of FIG. 5, after drying, a fully solidified multilayer preform 2 is obtained.
Since 60 parts by weight of the acrylic acid polymer is used with respect to 00 parts by weight, a considerable amount of solidified acrylic acid polymer exists between the stainless steel powders, and the space between the particles for forming the air holes is reduced. It also contributes to the maintenance and the maintenance of the pore diameter during sintering.

Next, another embodiment of the present invention will be described. <1> In the above embodiment, fine particles having an average particle size of 10 μm are arranged on the outer surface,
Although an example of manufacturing a filter having a minimum blocking particle size of 3 μm made of stainless steel and having coarse particles having a particle size distribution of m is shown, the particle material to be formed is not limited to the above, and is intended for application purposes. The particle size of the constituting particles is not limited to the above. In particular, the particles for forming the first layer are not limited to metals, and inorganic particles can be appropriately selected. For example, if oxidation catalyst particles are used as the inorganic particles, a filter having a catalytic action can be formed, and it can be formed as a simple catalyst carrier. <2> In the above-described embodiment, an example has been described in which the filter paper 7 is adhered to the inner surface of the mold body 3a and the metal-water slurry 5 is injected inside the filter paper 7; More preferably, the mold body 3a is immersed in a wax melting bath in which the wax has been melted, pulled up, and a brazing film is formed on the inner surface of the mold body 3a. A hole may be formed from the outside in the brazing film at the dehydration hole 3e of the mold body 3a in which the brazing film is formed on the inner surface. The mold 3 is assembled by attaching one end of a mold body 3a having a brazing film formed on the inner surface to a drive end plate 3b attached to a drive shaft 3d, and attaching an injection end plate 3c to the other end. do it. If heating is performed to promote the solidification of the binder, the brazing film is melted, and the multilayer preform 2 is released from the mold body 3a. Such a release material is not limited to wax, for example, synthetic resin powder, carbon particles, etc. can be applied,
The particles having a particle diameter of 100 μm or less are suitable, but both the material and the particle diameter can be arbitrarily selected. In short, it is only necessary that the mold release is easy and that it does not hinder molding. <3> In the above-described embodiment, in order to dehydrate through the dehydrating hole 3e of the mold main body 3a, a filter paper 7 is stuck on the inner surface of the mold main body 3a, and the metal-water slurry 5 is injected. Although an example in which dewatering is performed through the dewatering holes 7e formed in the mold body 3a through the filter paper 7 has been described, as shown in <2> above,
When a release material such as a brazing film is used, the vicinity of the inner surface of the mold body 3a of the injection-side end plate 3c is formed of a porous metal sintered body, and the filter paper 7 is not attached to the injection-side end plate 3c. Dehydration may be performed via the end plate 3c. Further, after the metal-water slurry 5 is supplied, the rotation at 1500 rpm is maintained for about one hour, and the metal-water slurry 5 is heated from the outside of the mold 3 for about 10 hours.
Although the example in which the metal-water slurry 5 is dried while being dehydrated while maintaining the temperature at 0 ° C. for about 12 hours has been described, the injection-side end plate 3c is formed of a porous metal sintered body, and the injection-side end plate 3c is formed. Dehydration may be performed via 3c. By doing so, the drying time can be shortened, and heating for the time required for curing the binder is sufficient. <4> In the above embodiment, an example was described in which an acrylic acid polymer was used as the binder, but the material of the binder is not limited to the above. Further, the slurry viscosity is preferably high according to the density and the particle size of the particles, but is not limited to the above viscosity. For example, the viscosity may be increased if the particle density is high or the particle size is large, and the viscosity may be decreased if the particle density is low or the particle size is small. The material of the binder can be appropriately selected. <5> In the above-described embodiment, an example has been described in which the particles for forming the first layer are supplied into the mold 3 as the solid-liquid mixture 4 in the form of a slurry. Only the particles for forming one layer may be supplied into the mold 3, and the medium liquid may be supplied later to form the solid-liquid mixture 4 in the mold 3. <6> In the above-described embodiment, an example has been described in which the metal-water slurry 5 is supplied to the inside of the first layer 1 after the first layer 1 is formed by dehydration. The metal-water slurry 5 may be supplied before completely dewatering. By doing so, an intermediate layer can be formed at the boundary between the first layer 1 and the particle layer for forming the second layer. By providing continuity in this way, the bonding between the layers of the metal tube after sintering can be further enhanced. <7> In the above-described embodiment, an example in which degreasing and sintering are continuously performed in the capsule has been described. However, after degreasing, the capsule may be sealed and sintered. Alternatively, sintering may be performed without encapsulation. <8> In the above embodiment, an example is shown in which the first layer forming particles and the second layer forming particles are formed by changing the particle size with the same material, but the first layer forming particles are used. And the particles for forming the second layer may be composed of different materials.
If the recrystallization temperature of the first layer forming particle material is set to be higher than the recrystallization temperature of the second layer forming particle material, when the metal filter is sintered, the first layer forming the filter layer is overheated. Sintering is easily prevented, and the control of the minimum blocking particle size is facilitated. <9> In the above-described embodiment, an example is shown in which the multilayer preform 2 is encapsulated and sintered under isostatic pressure, but sintering may be performed without encapsulation. By sintering in this manner, sintering can be performed without crushing the internal ventilation holes. In addition, the sintering of the multilayer preform 2 does not have to be performed under isostatic pressure. Depending on the material and particle size of the multilayer preform 2, sintering under normal pressure may be performed. Alternatively, vacuum sintering may be used.

In the claims, reference numerals are provided for convenience of comparison with the drawings, but the present invention is not limited to the configuration shown in the attached drawings.

[Brief description of the drawings]

FIG. 1 is an explanatory cross-sectional view showing an injection state of particles for forming a second layer showing an example of the present invention.

FIG. 2 is an explanatory view showing injection of a first layer into a centrifugal mold of the present invention.

FIG. 3 is an explanatory view showing a state where the particles for forming a second layer of FIG. 1 are dried after being injected.

FIG. 4 is an explanatory view of an example of a step of extracting a multilayer preform of the present invention.

FIG. 5 is an explanatory view showing a cross section of the multilayer preform.

FIG. 6 is an explanatory view of an example of a conventional manufacturing process of a porous sintered metal tube.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 1st layer 2 Multilayer preform 3 Mold

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Akira Kosaka 1-1-1, Nakamiya Oike, Hirakata City, Osaka Prefecture Inside Kubota Hirakata Manufacturing Co., Ltd. (72) Inventor Jun Funakoshi 1-1-1, Nakamiya Oike, Hirakata City, Osaka Prefecture No. 1 Kubota Hirakata Factory

Claims (6)

[Claims] 1. A method for producing a porous sintered metal tube for heating and sintering a preform, comprising a first-layer forming particle in a cylindrical mold (3) rotating at high speed. The solid-liquid mixture is charged and centrifugally formed to form a first layer (1), and metal particles for forming a second layer are supplied inside the first layer (1) to form the first layer (1). A method for producing a porous sintered metal tube in which a tubular multi-layer preform (2) formed integrally with 1) is formed and the multi-layer preform (2) is sintered. 2. The first layer forming particles and water are slurried in advance and injected into the rotating mold (3) to form a solid-liquid mixed layer, and the solid-liquid mixed layer is solidified. After the formation of the first layer (1), a metal-water slurry prepared by adding water to the metal particles for forming the second layer in advance is poured into the inside of the first layer (1) and dehydrated. The porous sintered metal tube according to claim 1, wherein the layer made of the metal particles for forming the second layer is integrated with the first layer (1) to solidify and form the multilayer preform (2). Manufacturing method. 3. A method for producing a porous sintered metal tube for heating and sintering a preform, wherein particles for forming a first layer are dispersed in a cylindrical mold (3) rotating at high speed. Thereafter, water to which a binder has been added is added to the particles for forming the first layer after the spraying to form a solid-liquid mixed layer, and the solid-liquid mixed layer is solidified to form a first layer (1). The metal particles for forming the second layer are supplied to the inside of the first layer (1) thus formed, and the layer composed of the metal particles for forming the second layer is converted to the first layer.
A method for producing a porous sintered metal tube, wherein a multilayer preform (2) is formed by integrating with a layer (1), and the multilayer preform (2) is sintered. 4. The method according to claim 1, wherein inorganic particles are used as the first layer forming particles, and metal particles having a larger particle diameter than the first layer forming particles are used as the second layer forming metal particles. The method for producing a porous sintered metal tube according to any one of the above. 5. The method according to claim 5, wherein the particles for forming the first layer are the second particles.
The method for producing a porous sintered metal tube according to any one of claims 1 to 4, wherein the first metal particles having a recrystallization temperature higher than a recrystallization temperature of the layer-forming metal particles are used. 6. The method for producing a porous sintered metal tube according to claim 1, wherein the multilayer preform (2) is sintered under isostatic pressure.